An Experimental Study on Rotor Aerodynamic Noise Control Based on Active Flap Control

Reducing rotor aerodynamic noise is an important challenge in helicopter design. Active flap control (AFC) on rotors effective reduction method. It changes the segment airfoil shape, load distribution, and wake path of flow by adding trailing edge flaps (TEFs). Although AFC easily simulated, relevant experiments have not been widely conducted due to test technical problems limited financial support. The acoustic characteristics AFC-equipped rotor, such as placement TEFs for whether multiple winglets can provide a better effect than single winglets, verified previous experiments. In this work, with two was designed, its properties were tested FL-17 wind tunnel microphone arrays far field. results showed that closely related frequency phase. Increasing phase could move region toward azimuth-decreasing far-field noise. outboard TEF inboard TEF, while dual-TEF model performed better. experiment, average observation point at lower front be more 3 dB, maximum 6.2 dB.